Historical Changes in Frequency and Seasonality of Extreme Floods In

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This discussion paper is/has been under review for the journal Hydrology and Earth System Historical changes in Sciences (HESS). Please refer to the corresponding final paper in HESS if available. frequency and seasonality of extreme floods in Historical changes in frequency and Prague seasonality of extreme floods in Prague L. Elleder

L. Elleder

Czech Hydrometeorological Institute, Prague, Czech Republic Title Page

Received: 22 December 2014 – Accepted: 9 January 2015 – Published: 4 February 2015 Abstract Introduction Correspondence to: L. Elleder ([email protected]) Conclusions References

Published by Copernicus Publications on behalf of the European Geosciences Union. Tables Figures

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1633 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion Abstract HESSD This study presents a flood frequency analysis for the Vltava River catchment using a major profile in Prague. The estimates of peak discharges for the pre-instrumental 12, 1633–1652, 2015 period of 1118–1824 based on documentary sources were carried out using different 5 approaches. 187 flood peak discharges derived for the pre-instrumental period aug- Historical changes in mented 150 records for the instrumental period of 1825–2013. Flood selection was frequency and based on Q10 criteria. Six flood-rich periods in total were identified for 1118–2013. Re- seasonality of sults of this study correspond with similar studies published earlier for some Central extreme floods in European catchments, except for the period around 1750. Presented results indicate Prague 10 that the territory of the present Czech Republic might have experienced in the past, L. Elleder extreme floods comparable, with regard to peak discharge (POTQ10) and frequency, to the flood events recorded recently.

Title Page 1 Introduction Abstract Introduction

Research of historic floods significantly enhances our ability to better understand the Conclusions References 15 behaviour of recent flood events in the context of global environmental change. Numer- ous studies have focused on this issue in last two decades (e.g. Brázdil et al., 2006b; Tables Figures Glaser et al., 2010). In the Czech Republic, four extreme summer floods were recorded within the last J I 15 years (1997, 2002, 2010, and 2013). Two of these were classified as 500 year or J I 20 even 1000 year events (Hladny´ et al., 2005; Blösch et al., 2003); two out of the four stroke the Vltava River catchment. Taking into account the entire region of Central Back Close

Europe, further extreme summer ﬂoods can be added: in the Alps in 2005, and in Full Screen / Esc Slovakia and Poland in 2010. An interesting question thus emerges as to whether there

is an analogy with a similar frequency of important or extreme floods in the past. The Printer-friendly Version 25 aim of this contribution is to answer two scientific questions: (1) has the territory of the present Czech Republic experienced four summer extreme flood events within a mere Interactive Discussion 1634 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion 15 year period earlier in history? (2) Did the region of Central Europe record extreme large-scale floods during the last 500 years more often when compared to the present? HESSD Prague is, with respect to floods, a key point for Central Europe. It represents a clos- 12, 1633–1652, 2015 ing profile of the Vltava River, the most important tributary of the Elbe River. As com- 5 pared to other major Elbe tributaries, such as the Saale, Spree, and the Elster, with respect to the catchment area, average discharge and Q100, the Vltava River can be Historical changes in regarded as the most significant one. According to the above criteria, the Vltava River frequency and is even more significant as compared to the upper part of the Elbe River, where it flows seasonality of to, 40 km downstream of Prague, at the town of Mělník. Q100 values of the Otava and extreme floods in 10 Berounka Rivers, the most important tributaries of the Vltava River, correspond merely Prague to the Q2– Q5 levels (Table 1). Interestingly, this also applies for the Elbe River prior to the confluence with the Vltava River, which implies that the Elbe River is a tributary L. Elleder of the Vltava River rather than the other way around (Table 1). These facts are abso- lutely essential for the examination of historical floods. According to the facts above, the Title Page 15 Vltava River floods significantly influence the Elbe River floods, at least up to Torgau (before confluence with the Mulde and Saale River and Magdeburg) in Germany. There Abstract Introduction is a strong association between the peak discharges in Prague and the Elbe profiles Conclusions References in Northern Bohemia, and in Saxony – Pirna, Dresden, and Meissen (Elleder, 2013). A crucial issue for the presented study is that the flood marks and records of historic Tables Figures 20 floods (Fig. 1) going back to 1432 are available for these sites (Brázdil et al., 2005; Fügner, 2006). In this study, Prague represents the major profile, while other profiles J I were used to supplement it, and for verification of the final estimates. J I

Back Close 2 Methods Full Screen / Esc 2.1 Input data Printer-friendly Version 25 For the Vltava River catchment, 159 peak discharge records for the period between 1118 and 1825, when the regular daily water level measurements began, are available Interactive Discussion 1635 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion (Brázdil et al., 2005). The most reliable 18 cases, associated with summer floods, are related to the flood marks and original Prague water gauge denoted as “the Bearded HESSD Man” used since (1481 Elleder, 2004). Novotny´ (1963) presented an additional 121 12, 1633–1652, 2015 peak discharges (1825–1953) for the period before the Vltava River Cascade construc- 5 tion. The peak discharges from 1825 to 1880 were assessed earlier, with an assump- tion of the 1880–1890 rating curve validity (Richter, 1892). Water levels for Prague Historical changes in after 1954 are in the Czech Hydrometeorological Institute database, concurrently in frequency and simulation without the influence of the Vltava River dams (Kašpárek et al., 2005). seasonality of The 2012 flood, with peak discharge of 5160 m3 s−1, is the most important case extreme floods in 10 over the instrumental period (Hladny´ et al., 2005). Interestingly, the flood of July 1432 Prague was likely even more important (Elleder, 2010; Daňhelka, 2012). For other significant L. Elleder historic floods – bigger than Q50 – in the Vltava River catchment, Brázdil et al. (2005) published brief descriptions. Detailed papers, though most of them only in Czech, were published for the following floods: 1432 (Daňhelka, 2012), 1582 (Elleder and Kotyza, Title Page 15 2007), 1714 (Elleder et al., 2014), 1784 (Munzar et al., 2014), 1830 (Munzar, 2000), 1845 (Kakos and Kulasová, 1995), 1862 (Elleder et al., 2012b), 1872 (Elleder et al., Abstract Introduction 2012a), and the 1890 (Kakos, 1990). Regretfully, the extreme flood cases, such as Conclusions References 1501, 1598, 1655, 1675, 1799, and 1824, have not been evaluated so far. For archiving of documentary sources related to floods over the Czech territory, the author has been Tables Figures 20 developing a private relation database system “Krolmus” since 2000. J I 2.2 Major Vltava River profile in Prague and its changes over time J I The major Vltava River profile for Prague until 1825 was the monastery of the Knights Back Close with Red Star past the Charles Bridge; after 1825 with the beginning of the systematic water level measurements it was the Old Town Mills profile before the Charles Bridge. Full Screen / Esc 25 The entire period under review, 1118–2013, has been divided into seven periods (P1– P7), with respect both to the reliability of input data and changes in the area near Printer-friendly Version

the major profile. The least reliable data are these relating to 1118–1350 (P1). After Interactive Discussion the construction of the new town walls (1250–1300) and reconstruction of the city, 1636 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion the Old Town terrain was more or less stabilized (Hrdlička, 2001). In 1351–1480 (P2) some floods are recorded as related to important town buildings (Table 2). During this HESSD period, the number and height of Prague weirs were fixed. In 1481–1780 (P3) the 12, 1633–1652, 2015 records of water levels are available. Since 1481 these are related to the “Bearded 5 Man” water gauge (Elleder, 2004, 2012). Since 1501 flood marks started to appear, but those from 1501 and 1655 were destroyed, and currently flood marks since 1675 are Historical changes in preserved (Brázdil et al., 2005). Changes between the 16th and the mid19th century frequency and were minor (Elleder et al., 2012). The first modern water gauge in Prague was set up seasonality of in 1781 (Brázdil et al., 2005; Elleder, 2010). Systematic records date back to 1825. extreme floods in 10 The next 60 year period of 1781–1843 (P4) until the construction of the Vltava River Prague embankment is used for calibration of the relation between measured water stages during flood events and flood impacts, such as the flooded area (Elleder, 2010). For the L. Elleder next period of 1844–1909 (P5), when the Vltava River embankment construction was undertaken, a rating curve is available. In 1910–1926 (P6a) the inundated area of the Title Page 15 Old Town was raised to the embankment. In the next period 1927–1953 (P6b) no major changes occurred until construction of the Vltava River cascade dam. Construction Abstract Introduction of the Vltava River dam cascade in 1954–1961 resulted in a crucial change of the Conclusions References hydrological regime (Kašpárek and Bušek, 1990). The current period 1954–2013 (P7) has been affected by implementation of the cascade. Until mobile dikes were put into Tables Figures 20 operation (2010–2013), no major changes were undertaken in Prague. J I 2.3 Peak discharge estimates based on hydraulic calculation J I Reliable records of 18 summer floods from 1481–1825 were assessed using a hy- Back Close draulic approach, similar to that applied by Herget at al. (2010) for German Cologne. Herget et al. (2014) recommended support of the hydraulic approach with detailed Full Screen / Esc 25 knowledge of river cross-section and flood plain, and use of the Manning equation (Chow, 1959). The results of this approach for Prague were published earlier by Elleder Printer-friendly Version

et al. (2012). This evaluation, however, did not include winter floods, or flood events Interactive Discussion with less reliable or roughly estimated water level records. The objective of this study 1637 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion was the utilization of most of the data with an acceptable level of reliability for flood seasonality analysis. HESSD

2.4 Other interpreted data 12, 1633–1652, 2015

Relations between water stage or peak discharge and impacts relevant for P5 and Historical changes in 5 P6 periods (Elleder, 2012) were applied for the interpretation of historic floods. The frequency and rating curve for 1880–1890 (Richter, 1892) was used for P3 floods – events with a fairly seasonality of reliably documented water level. extreme floods in For winter floods, a problematic association between water level and discharge due Prague to ice jamming is to be accounted for. No case, nevertheless, with a higher water level 10 due to ice jamming, as compared to subsequent water level due to flood discharge, is L. Elleder known for Prague. For POTQ10, the discharge was always sufficient for an ice barrier release. This holds for the 1784 February flood (Elleder, 2000), and also for all recorded winter floods during 1800–1850 (Fritsch, 1850). It is particularly true for the Prague Title Page profile, but does not hold, in any case, for supporting profiles in Děčín, Dresden, and Abstract Introduction 15 Meissen. Supporting profiles in the upper Vltava River (České Budějovice, Beroun, Písek) Conclusions References were used for providing a balance of estimated discharges in the upper Vltava River, Tables Figures while supporting profiles downstream (Litoměřice, Děčín, Pirna, Dresden, Meissen) were used for regression estimates. This approach enabled the checking and specifi- J I 20 cation of not only estimated discharges, but also the time of flooding in Prague. In some cases, this approach facilitated even the filling in of the missing values. The credibility J I of discharges estimated by the approach above is undoubtedly lower than discharges Back Close derived from authentic description and records of flood in Prague. Full Screen / Esc 2.5 Selection of floods Printer-friendly Version 25 The results are presented for all floods, including events higher than or equal to Q2. Out of the total of 159 floods of B set (Brázdil et al., 2005), 13 events were excluded, Interactive Discussion 1638 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion as they were recorded merely for the Vltava River in České Budějovice, and without other supporting material, the assumed discharge in Prague is likely to be less than HESSD Q 2. 56 similar cases before 1852 are in the database. 12, 1633–1652, 2015 In the framework of the analysis, two approaches are to be distinguished: annual 5 Maximum Flood (AMF further in the text), and Peaks over Threshold (POT further in the text) approach. A perception threshold for recognising an event as a flood, and for Historical changes in frequency and drawing a flood mark, a discharge around Q10 was generally accepted in Prague until seasonality of 1781 (Table 2). That is the reason for establishing Q10 as a threshold for denoting the extreme floods in real extreme flood events, and the selection of such events is labelled POTQ10. Prague

10 3 Results and discussion L. Elleder

3.1 Frequency of floods over the centuries Title Page The time-series of measured peak discharges from 1825–1954 for Prague available (Novotny,´ 1960) was extrapolated by 187 flood events for the pre-instrumental period Abstract Introduction using the documentary data. These 187 events represent, however, only 149 years with Conclusions References 15 floods, as in 23 years floods were recorded 2–3 times annually. The total time-series include some 350 peak discharges in 306 years. After excluding the events equal to or Tables Figures lower than Q2, we have a set of 180 flood events (119 events before 1825). Figure 2 summarizes the frequency of floods over the centuries. The high variability J I

in Q2 flood events most likely does not reflect the reality – rather it is a consequence J I 20 of the fact that many of these “unimportant” floods were not recorded in the 12th–18th Back Close centuries. Considerable equilibrium is obvious in POTQ10 before 1500 (13 events in total, which means 6 events per century, on average), and after 1500 (55 events in total, Full Screen / Esc that means 11 events per century, on average). This set is representative for the period after 1500 at least, when POTQ10 can be considered a good approximation of the real Printer-friendly Version 25 count of floods. The highest occurrence of POTQ10 flood events was recorded in the 16th century (14 events), and in the 19th century (15 events). The 17th and 18th cen- Interactive Discussion 1639 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion turies can be reckoned as average centuries, with 10, and 9 flood events, respectively. Interestingly, a low number of flood events was recorded in the 20th century (4 flood HESSD events). In contrast, the high frequency of floods is striking in the 14th century, when 12, 1633–1652, 2015 some 6 cases might have reached Q50 level. Flood frequency is obviously low in the 5 21st century with respect to the number of years. It is notable, however, that we have already seen three POTQ10 floods within 13 years, one in four years on average. Historical changes in frequency and 3.2 Periods with high flood frequency within European context seasonality of extreme floods in Figure 3 presents an overview of all floods – about 300 AMF. For more accurate iden- Prague tification of periods with high flood frequencies, a 31 year running sum was used. The 10 exceedance of POTQ10 defines flood-rich periods (FRP, further in the text). Six periods L. Elleder and two sub-periods, with minimal overlap with respect to Q50–Q500 occurrence, were identified in total. Some significant floods in P1 (1118, 1272, 1273), and P2 (1432) are not included in the above periods. This fact is most likely a consequence of the lack of Title Page documentary sources for P1 and P2 periods. It holds, however, also for the beginning Abstract Introduction 15 of the P3 period with the extreme flood of 1501. POTQ10 floods recorded in the Vltava River affected a major part of Central Europe as well, at least two or three major catch- Conclusions References ments out of five: the Elbe, Danube Oder, Wesser, Warta. These floods can be labelled Tables Figures as Central European Floods (CEF, further in the text). An example of such a CEF is the 1374 flood (FRP1), which is recorded, apart from J I 20 the Vltava River, also in the Saale catchment (Deutch and Portge, 2003), and the Rhine catchment (Herget, 2010). Synchronic winter floods (1655, 1682, 1784, 1799, J I 1862, 1876) were recorded by flood mark on the Main (Eibelstadt, Frankfurt am Main, Back Close etc.), the Danube (1682, 1784, 1799, 1830, 1862), and the Rhine (1651, 1784, 1799). For summer floods, an association with the Danube and Oder catchments is more Full Screen / Esc 25 common. Frequently, the Alpine tributaries of the Danube – the Innn, Enns, Traun – or the Danube itself between Passau and Vienna (1501, 1569, 1598, 1890, 2002, Printer-friendly Version

2013) are involved. Flood marks of these are found at numerous sites (Linz, Schärding, Interactive Discussion Burghausen, Steyer). Synchronic floods with the Vltava River for some Oder tributaries 1640 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion (Nysa Łużycka (Lausitzer Neiße), Kwisa, Bóbr, Kaczawa, and Nysa Klodzka) for 1359, 1387, 1432, 1501, 1563, 1564, 1567, 1569 are presented by Gyrgus and Strupczewski HESSD (1965). 12, 1633–1652, 2015 In cases when other catchments (the Seine, Loire, Maas) were also affected, the 5 acronym WCEF (West-Central European flood) is used. These are, for example, 1658, 1740, 1784, and 1799 winter floods (Elleder, 2010). Historical changes in The overview of the identified periods with high flood frequencies with relevant flood frequency and events is presented below. seasonality of extreme floods in 3.2.1 Period FRP1 (1350–1390), (7 flood events/40 years) Prague

10 It includes summer ﬂoods of 1359 (CEF), 1370, and 1387 (CEF) and winter ﬂoods of L. Elleder 1367, 1370, 1373, and 1374 (CEF).

3.2.2 Period FRP2 (1560–1600), (12 ﬂood events/40 years) Title Page

Summer ﬂoods prevail in 1564, 1568, 1569 (CEF), 1575, 1582, 1587, and 1598 (CEF). Abstract Introduction

Winter ﬂoods in 1570, and 1595 (CEF). Conclusions References

15 3.2.3 Period FRP3 (1650–1685), (6 ﬂood events/35 years) Tables Figures

Winter ﬂoods prevail in 1651 (CEF), 1655 (CEF), and 1682 (CEF). Flood in 1658 J I (WCEF) was recorded for Dresden. It is unclear, however, if the high peak discharge was not due to ice jamming. Summer ﬂoods in 1651 and 1675 have not been men- J I tioned so far outside of the Czech lands. Back Close

20 3.2.4 Period FRP4a (1770–1800), (6 ﬂood events/35 years) Full Screen / Esc

Winter ﬂoods prevail in 1770, 1771, 1782, 1784 (WCEF), 1785 (CEF), 1799 (WCEF). Printer-friendly Version

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1641 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion 3.2.5 Period FRP4b (1805–1830), (6 flood events/30 years) HESSD Winter floods in 1809, 1810, 1827, 1830 (CEF), and summer floods in 1804, and 1824. 12, 1633–1652, 2015 3.2.6 Period FRP5a (1845–1880), (5 flood events/35 years) Historical changes in Winter floods prevail in 1845 (CEF), 1862 (CEF), 1865, and 1876 (CEF). Summer flood frequency and 5 of 1872 was a flash flood with extreme intensity. This flood is related to the floods on the seasonality of upper Rhine and Po tributaries (Elleder, 2012). This period includes a catastrophic flood extreme floods in on the Elbe River in February 1846, and a no less deleterious flood in August 1858. Prague 3.2.7 Period FRP5b (1881–1920), (6 flood events/40 years) L. Elleder Summer floods dominate in 1890 (CEF), 1896, and 1915. In the Czech lands, there 10 were simultaneous catastrophic floods, particularly in the Elbe catchment, in August Title Page and September 1888, 1897 (CEF), and 1899 (CEF), that reached a mere Q5 in the Vltava River, however. Winter floods in 1882 (CEF), 1900, and 1920 (CEF). Abstract Introduction

3.2.8 Period FRP6 (starting 1994), (3 flood events/14 years) Conclusions References Tables Figures So far summer floods have prevailed in 2002 (CEF), and 2013 (CEF), after simulation 15 (removing of the Vltava dam cascade influence), also the 2006 flood can be included. J I The flood periods identified correspond, more or less, with similar periods for Central Europe published earlier. The period corresponding with FRP1 was reported for exam- J I

ple for the Isar River (Böhm and Wetzel, 2009), the Pegnitz, and the Rhine downstream Back Close the conﬂuence with the Mosela (Glaser et al., 2004). 20 Schmocker-Fackel and Naef (2009) assessed the ﬂood frequency in 14 catchments Full Screen / Esc across Switzerland. This was further extended by Böhm et al. (2014), who studied in more detail Bavarian Forealps. Flood-rich periods in Central European catchments Printer-friendly Version

(Glaser et al., 2008), correspond with FRP2–FRP4. This is not a surprising result, as Interactive Discussion the major floods in the Vltava River catchment were obviously part of extended CEF 1642 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion (likely more often than stated above), rarely of WCEF. Mostly the records are lacking, however. HESSD Results of this study show a minor peak around 1440–1450, which was recorded 12, 1633–1652, 2015 also in the Pegnitz River catchment (Glaser et al., 2004). This peak in Prague is asso- 5 ciated particularly with three extreme floods in 1432, and with 1434. Interestingly, one of these, the flood of August 1432 is comparable with the extreme 2002 flood (Brázdil Historical changes in et al., 2006a; Elleder, 2010; Daňhelka, 2012). frequency and There are also some discrepancies between the results of the presented study and seasonality of results published for other catchments. Surprisingly, one of the most prominent flood- extreme floods in 10 rich periods in the second half of the 16th century (FRP2) differs from the Isar and Prague Lech Rivers catchments (Böhm and Wetzel, 2009), which are, with respect to geogra- phy, very similar to the Vltava River catchment. Nevertheless, in the very next Danube L. Elleder tributaries – the Traun and Enns River catchments – flood events parallel to the Vltava River catchment were identified (Rohr, 2007). Title Page 15 Identified flood-rich periods correspond with decadal frequencies for Prague (Brázdil et al., 2005), except for the period around 1750. This discrepancy is closely related Abstract Introduction to POTQ selection. If the criteria for selection are strictly adhered to, only floods 10 Conclusions References from 1712, 1734, and 1736 may be identified. For this reason, the peak around 1750 is reduced. Nevertheless, in this period also a fairly high number of summer floods Tables Figures 20 with estimated peak discharge of Q5–Q10 (1751, 1755, and 1757) was recorded. If the peak discharge threshold were lower than Q10, the peak around 1750 would be higher, J I corresponding more to results of Brázdil et al. (2005), whose criteria of flood selection J I was Q2. With regard to flood frequency across the entire area of Central Europe, the present Back Close 25 flood-rich period began around 1994. Major floods were recorded in 1994, and 1995 Full Screen / Esc (the Rhine River: Engel, 1997), 1997 (the Oder River: Kundzewicz, 1999), 2002 (the Elbe and Danube Rivers: Hladny,´ 2005), 2005 (Upper Rhine and Danube tributaries: Printer-friendly Version Beniston, 2006), 2010 (the Oder and Vistula Rivers) and 2013 (the Elbe, Danube, and Oder Rivers: Blöschl et al., 2013). This makes six or seven major floods over 20 years, Interactive Discussion

1643 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion including one large-scale event in the vast region between the Rhine and Vistula Rivers. For such events, however, no comparable period was found in last 100–200 years of HESSD the instrumental period. This reason further enhances an interest in examining the 12, 1633–1652, 2015 pre-instrumental period in search for analogy with recent records. 5 The results of this study clearly show that currently available historical data do not allow for deriving detailed conclusions on flood frequency in Central Europe. Further Historical changes in analysis of single flood events for the whole affected area (such as in Brázdil et al., frequency and 2010; Munzar et al., 2010) are urgently needed to be more certain in this aspect. seasonality of extreme floods in Prague 4 Conclusions L. Elleder 10 The presented set of estimated flood peak discharges for Prague specifies results of previous studies. Peak discharge estimates made it possible to utilize also the data from the tributaries, and profiles situated downstream of the examined river profile. In Title Page contrast, some discharges lower than Q2 were excluded. That implies that the final set used for this study somewhat differed from data used for flood frequency analysis for Abstract Introduction 15 the Vltava River catchment earlier (Brázdil et al., 2005). Conclusions References In total, five historical periods with higher than POTQ10 flood frequency were identified. The time span for each of these five periods was some 35–40 years. Results Tables Figures of this study clearly show that POTQ10 flood is likely to occur 6–12 times in a period of higher flood frequency, which means every third (in the 16th century) to eighth (in J I

20 the 19th century) year on average. Additionally, during the current period, in the Vltava J I River catchment we have recorded three major floods within 12 years (2002, 2006, and 2013), which means one in four years on average. Back Close To summarize: the results of the presented analysis indicate that the territory of the Full Screen / Esc present Czech Republic might have experienced in the past extreme floods compara- 25 ble, with regard to peak discharge (POTQ10) and frequency, to flood events recorded Printer-friendly Version recently. With respect to Central Europe considered as a whole, the existence of a similar period can be fairly reasonably assumed at least for the 16th century. It cannot be Interactive Discussion 1644 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion excluded, however, that one more or even several more periods of extreme floods over a relatively short time span, occurred in the past. As a matter of fact, the historical data HESSD available presently do not allow an unambiguous conclusion on this issue. 12, 1633–1652, 2015 Acknowledgements. The author thanks his colleague Jolana Šírová for preparing Fig. 1. Historical changes in frequency and 5 References seasonality of Beniston, M.: August 2005 intense rainfall event in Switzerland: not necessarily an analog extreme floods in for strong convective events in a greenhouse climate, Geophys. Res. Let., 33, L05701, Prague doi:10.1029/2005GL025573, 2006. Blöschl, G., Nester, T., Komma, J., Parajka, J., and Perdigão, R. A. P.: The June 2013 flood in L. Elleder 10 the Upper Danube Basin, and comparisons with the 2002, 1954 and 1899 floods, Hydrol. Earth Syst. Sci., 17, 5197–5212, doi:10.5194/hess-17-5197-2013, 2013. Brázdil, R., Glaser, R., Pfister, C., Dobrovolny,´ P., Antoine, J.-M., Barriendos, M., Camuffo, D., Title Page Deutsch, M., Enzi, S., Guidoboni, E., Kotyza, O., and Sanchez Rodrigo, F.: Flood events of selected European rivers in the sixteenth century, Climatic Change, 43, 239–285, 1999. Abstract Introduction 15 Brázdil, R., Dobrovolny,´ P.,Elleder, L., Kakos, V., Kotyza, O., Kveton, V., Macková, J., Müller, M., Štekl, J., Tolasz, R., and Valášek, H.: Historical and Recent Floods in the Czech Republic, Conclusions References Masaryk University/Czech Hydrometeorological Institut, Brno, Prague, 2005. Tables Figures Brázdil, R., Kotyza, O., Dobrovolny,´ P.: July 1432 and August 2002 – two millennial floods in Bohemia?, Hydrolog. Sci. J., 51, 848–861, 2006a. 20 Brázdil, R., Kundzewicz, Z. W., and Benito, G.: Historical hydrology for studying flood risk in J I Europe, Hydrolog. Sci. J., 51, 739–764, 2006b. J I Brázdil, R., Demarée, G. R., Deutsch, M., Garnier, E., Kiss, A., Luterbacher, J, Macdonald, N., Rohr, C., Dobrovolny,´ P.,Kolář, P.,Chromá, K.: European floods during the winter 1783/1784: Back Close scenarios of an extreme event during the “Little Ice Age”, Theor. Appl. Climatol., 100, 163– Full Screen / Esc 25 189, 2010. Chow, V. T.: Open Channel Hydraulics, McGraw-Hill, New York, 1959. Deutsch, M. and Pörtge, K. H.: Hochwasserereignisse in Thüringen, Ministerium für Land- Printer-friendly Version wirtschaft, Naturschutz und Umwelt, Freistaat Thüringen, Jena, 2003. Elleder, L.: Pražsky´ Bradáč, jeho stáří, účel a historie, Historica Pragensia, 1, 301–333, 2003. Interactive Discussion 1645 icsinPpr|Dsuso ae icsinPpr|Dsuso ae | Paper Discussion | Paper Discussion | Paper Discussion | Paper Discussion Elleder, L.: Reconstruction of the 1784 flood hydrograph for the Vltava River in Prague, Czech Republic, Global Planet. Change, 70, 117–124, 2010. HESSD Elleder, L., Herget, J., Roggenkamp, T., and Nießen, A.: Historic floods in the city of Prague – reconstruction of peak discharges, Hydrol. Res., 44, 202–214, 2013. 12, 1633–1652, 2015 5 Engel, H.: The flood events of 1993/1994 and 1995 in the Rhine River basin, in: Destructive Wa- ter: Water-Caused Natural Disasters, their Abatement and Control, IAHS Publication no. 239, edited by: Leavesly, G. H., Lins, H. F., Nobilis, F., Parker, R. S., Schneider, V. R., and Van de Historical changes in Ven, F. H. M., IAHS Press, Wallingford, UK, 1997. frequency and Fügner, D.: Historische Hochwasser-Marken des Elbestromes, BMBF-Projekt: “Integration von seasonality of 10 historischen und hydrologisch/ hydraulischen Analysen zur Verbesserung der regionalen extreme floods in Gefährdungsabschätzung und zur Erhöhung des Hochwasserbewusstseins”, BTU Cottbus, Prague Cottbus, 2007. Glaser, R., Stangel, H., and Lang, M.: Floods in Central Europe since AD 1300 and their re- L. 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Historical changes in frequency and seasonality of extreme ﬂoods in Prague

L. Elleder

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Historical changes in frequency and seasonality of extreme ﬂoods in Table 1. Important data on ﬂoods in the Elbe catchment. Prague

L. Elleder Water gauge Brandys´ n. L. Č. Budějovice Beroun Písek Praha Děčín River Elbe Vltava Berounka Otava Vltava Elbe 2 A [km ] 13 109 2850 8286 2913 26 730 51 104 Title Page 3 −1 Qa [m s ] 99 27.6 35.6 201 145 309 3 −1 Abstract Introduction Q2 [m s ] 572 572 403 300 1220 1720 3 −1 Q5 [m s ] 754 350 615 300 1770 2300 Conclusions References 3 −1 Q10 [m s ] 895 452 799 394 2230 2760 3 −1 Tables Figures Q50 [m s ] 1230 751 1310 680 3440 3900 3 −1 Q100 [m s ] 1390 908 1560 837 4020 4410 J I

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Historical changes in frequency and seasonality of extreme ﬂoods in Prague Table 2. Selected important sites with relations between water levels and peak discharges. L. Elleder Site Rec. interval H [cm] Q [m3 s−1]

(SM), Oldtown mill Q10 270 2200 Title Page (A) Nunnery of St. Ann Q10−20 250–320 2200–2500 (V) St. Valentin-ﬂoor Q10−20 300 2400 Abstract Introduction (L) St. Linhart Q50 > 400 > 3500 Conclusions References (Ag) St. Agidius Q100 > 480 > 4100 Q > > (N) St. Nicolaus 100 500 4500 Tables Figures (OS) Old Town Square > Q100 > 580 > 5000

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Historical changes in frequency and seasonality of extreme ﬂoods in Prague

L. Elleder

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Figure 1. The Vltava River catchment. The major tributaries and sites with records of historic Back Close ﬂoods and ﬂood marks are highlighted. Full Screen / Esc

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Historical changes in frequency and seasonality of extreme ﬂoods in Prague

L. Elleder

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Back Close Figure 2. Frequency of ﬂoods in Prague over the centuries. Full Screen / Esc

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Historical changes in frequency and seasonality of extreme ﬂoods in Prague

L. Elleder

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J I Figure 3. Final time-series presenting running 31 year frequencies in summer and winter ﬂoods Back Close in Prague. Full Screen / Esc

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